Quark Catalyst is a Macintosh Finder-like GUI desktop for the Apple
IIe. I have not been able to try this software myself, but a while back
these screen photos surfaced. Hats off to Blake Patterson who managed to
acquire this rare piece of software and posted these photos of it in operation
on his Flickr
page.

Catalyst 3 was produced around 1985 by Quark, inc which is more famous
for another product: Quark Express. It was bundled with early Apple 3.5"
UniDisk floppy drives for the Apple IIe. The original floppy disks contain
a form of copy "protection" that apparently prevents it from being read
in later 3.5" drives, and no version is known to exist that can be used
in emulators.

Catalyst was primarily a tool for running 5.25" floppy disk based applications
from a hard disk drive or the higher capacity 3.5" disks. (Many 5.25" disk
Apple software of the day used custom self-contained disk OSes that often
did not inter operate with the standard AppleSoft DOS or ProDOS.) Versions
1 and 2 were text-mode based, version 3 added the Mac like desktop.

At the time it competed with MouseDesk (Apple II Desktop) and looks
very similar, but the two are not related.

This is the "About" screen. Like the Macintosh desktop, icons representing
the disk drives appear directly on the desktop as does a "Trash" icon.
Although not specifically an Apple product, it uses an Apple logo for the
first menu item.

Files are displayed as icons in folder windows. Different icons are
displayed based on the ProDOS file types.

It is hard to tell from these screen shots if file management, such
as dragging and dropping, works like one would expect.

A few of the menu items. It is not clear if its ability to load disk-based
software to hard disks is built directly in to the desktop or separate
functionality.

Of course it mimics several of the Macintosh accessories. Shown here
are a calculator, clock, and sliding puzzle.

And a couple additional photos, first a brief advertisement for Catalyst
and another one of Quark's products "Word Juggler".